In Internet protocol (hereinafter referred to as IP)/Multi-protocol Label Switching (hereinafter referred to as MPLS) network of data communications, after an MPLS Label-Switched Path (hereinafter referred to as LSP) between two Label-Switch Routers (hereinafter referred to LSR) is established, if the links or node passed by LSP failed, communication link interruption and loss of user data will be caused. This kind of simple LSP can not satisfy user's requirements if the user has higher requirements on reliability of transmitted data.
In the art, in order to provide higher reliability to user data, end-to-end protection mode and Fast Reroute (hereinafter referred to as FRR) mode are usually adopted to ensure the reliability of the user data. The end-to-end protection mode, also known as path backup, realizes the whole protection from ingress node to egress node of LSP. When a failure on a main LSP is detected, the protection of the service data is realized through switching to a backup LSP or rebuilding a new backup LSP. FRR mode protects a link or a node passed by a main LSP by building a backup LSP in advance. When a failure on the protected link or node is detected, the flow on the main path is switched to the backup path to realize the protection of service data.
When the protection is performed using the above two protection modes, the relationship between the backup path and the main path needs to be considered to avoid that the backup path and the main path choose the same link. But in practical network, the main path and the backup path usually belong to the same interface group or the same equipment room, and when the main path fails, it is highly likely that the backup path fails as well. Based on this technical problem, Shared Risk Link Groups (hereinafter referred to as SRLG) information is used in the art. While a user assigns same SRLG information to two links, the two links are identified that they take the same risk and might be interrupted at the same time when encountering a failure. Therefore, when a protection path is selected, the other link should be ruled out. In this way, in practical networking, in order to get rid of, according to SRLG information, the links which take the shared risk, the path information in the Interior Gateway Protocols (hereinafter referred to as IGP) domain can be obtained according to the protocol of Constrained Shortest Path First (hereinafter referred to as CSPF), and the computation is performed according to the SRLG information configured by the user, thereby establishing the best backup path.
However, the technical solution in the art, which computes and establishes the best backup path according to the SRLG information, is applied to obtain the best backup path in an IGP domain. Since the path information of other domains can not be obtained, the above-mentioned technical solution can not be applied to obtain the best backup path under the cross-IGP domain scenario, which leads to lower safety of user data under the cross domain scenario.